Technical Field
The present disclosure relates to a converter, and more particularly, to a multi-phase interleaved converter and a control method thereof.
Background Art
An interleaved converter is a converter that is capable of reducing the amplitude of a whole current ripple due to a cancellation effect between currents, caused by the multi-division of current flow and the generation of phase differences. The interleaved converter is advantageously capable of reducing the capacity and volume of an input/output filter.
FIGS. 1 and 2 are views showing current control methods of related art interleaved converters. VO represents an output voltage, IA, IB and IC respectively represent phase currents, and DA, DB and DC respectively represent phase duty ratios (IX: X-phase current, and DX: X-phase duty ratio). Generally, the current control technique of a multi-phase interleaved converter uses two methods as shown in FIGS. 1 and 2.
The first method is most frequently used, and, as shown in FIG. 1, is a method in which one voltage controller 24 is utilized, and as many current controllers 21, 22 and 23 are utilized as the number of the phases. That is, in this method, current controllers 21, 22 and 23 for the respective phases are utilized. Thus, the current controllers 21, 22 and 23 receive sensed currents IA, IB and IC of the phases to generate duty ratio signals DA, DB and DC for controlling converters for the phases, respectively. Further, the current controllers 21, 22 and 23 are individually applied, thereby achieving current balance. However, there exists a problem in that the load factor of a microcomputer (MICOM) increases.
The second method is a method in which one voltage controller 24 and one current controller 21 are utilized as shown in FIG. 2. In this method, the current controller 21 receives sensed current IA of a first phase to generate a duty ratio DA by performing current control on the first phase, and the other phases are controlled by phase-shifting signals DB and DC having the same duty ratio to a predetermined size (different depending on the number of phases). The current controller 21 of the first phase is used, and hence changes in currents of the other phases are not instantaneously and exactly reflected. As a result, current imbalance may be created.
More specifically, the interleaved converter of FIG. 1 converts an output VIN output from an input voltage source 30, using a multi-phase interleaved converter 10, and transmits the converted output to an output terminal. In this state, an interleaved controller 20 controlling converters 11, 12 and 13 taking charge of the respective phases is provided with the current controllers 21, 22 and 23 for the converters 11, 12 and 13 taking charge of the respective phases. That is, a current controller 21 taking charge of phase A is provided to a sub-circuit 11 taking charge of the phase A, a current controller 22 taking charge of phase B is provided to a sub-circuit 12 taking charge of the phase B and, a current controller 23 taking charge of phase C is provided to a sub-circuit 13 taking charge of the phase C.
In the interleaved converter configured as described above, the voltage controller 24 measures a voltage VO of an output terminal capacitor 40, and transmits the measured voltage to each of the current controllers 21, 22 and 23. The current controllers 21, 22 and 23 for the respective phases generate duty ratio signals DA, DB and DC controlling the respective phases, and transmit the generated duty ratios to the interleaved converter 10, thereby controlling current output from the converter. Thus, the current controllers 21, 22 and 23 taking charge of the respective phases facilitate a the balancing of the inductor. However, there exists a problem in that the load factor of the MICOM increases.
FIG. 2 is a view showing a case where only one current controller is provided in the current control method. The interleaved converter of FIG. 2 also transmits an output VIN from the input voltage source 30 to an output terminal, using the multi-phase interleaved converter 10. In this state, the interleaved controller 20 controlling the converters 11, 12 and 13 taking charge of the respective phases is provided with only one current controller 21.
The interleaved converters 12 and 13 of the other phases are controlled by phase-shifting an output signal from the one current controller 21. That is, when the current controller 21 takes charge of the phase A, the converters 12 and 13 respectively taking charge of the phases B and C can phase-shift the signal output from the current controller 21 taking charge of the phase A by 120 degrees and 240 degrees, using phase shifters 25 and 26, and the phase-shifted signals are used for controls of the phases B and C, respectively.
In other words, a duty ratio DA for controlling current of one phase using the one current controller 21, and the other two phases are controlled by respectively phase-shifting signals DB and DC having the same duty ratio by 120 degrees and 240 degrees through phase shifters 25 and 26, respectively. In this method, the load factor of the MICOM can be reduced, but changes in currents of the other phases are not instantaneously and exactly reflected. Therefore, current imbalance may be created